/*!
  * Stickyfill – `position: sticky` polyfill
  * v. 2.1.0 | https://github.com/wilddeer/stickyfill
  * MIT License
  */

 ;(function(window, document) {
  'use strict';
  
  /*
   * 1. Check if the browser supports `position: sticky` natively or is too old to run the polyfill.
   *    If either of these is the case set `seppuku` flag. It will be checked later to disable key features
   *    of the polyfill, but the API will remain functional to avoid breaking things.
   */
  
  var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
  
  function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
  
  var seppuku = false;
  
  var isWindowDefined = typeof window !== 'undefined';
  
  // The polyfill can’t function properly without `window` or `window.getComputedStyle`.
  if (!isWindowDefined || !window.getComputedStyle) seppuku = true;
  // Dont’t get in a way if the browser supports `position: sticky` natively.
  else {
          (function () {
              console.log('支持fill')
              var testNode = document.createElement('div');
  
              if (['', '-webkit-', '-moz-', '-ms-'].some(function (prefix) {
                  try {
                      testNode.style.position = prefix + 'sticky';
                  } catch (e) {}
  
                  return testNode.style.position != '';
              })) seppuku = false;
          })();
      }
  
  /*
   * 2. “Global” vars used across the polyfill
   */
  var isInitialized = false;
  
  // Check if Shadow Root constructor exists to make further checks simpler
  var shadowRootExists = typeof ShadowRoot !== 'undefined';
  
  // Last saved scroll position
  var scroll = {
      top: null,
      left: null
  };
  
  // Array of created Sticky instances
  var stickies = [];
  
  /*
   * 3. Utility functions
   */
  function extend(targetObj, sourceObject) {
      for (var key in sourceObject) {
          if (sourceObject.hasOwnProperty(key)) {
              targetObj[key] = sourceObject[key];
          }
      }
  }
  
  function parseNumeric(val) {
      return parseFloat(val) || 0;
  }
  
  function getDocOffsetTop(node) {
      var docOffsetTop = 0;
  
      while (node) {
          docOffsetTop += node.offsetTop;
          node = node.offsetParent;
      }
  
      return docOffsetTop;
  }
  
  /*
   * 4. Sticky class
   */
  
  var Sticky = function () {
      function Sticky(node) {
          _classCallCheck(this, Sticky);
  
          if (!(node instanceof HTMLElement)) throw new Error('First argument must be HTMLElement');
          if (stickies.some(function (sticky) {
              return sticky._node === node;
          })) throw new Error('Stickyfill is already applied to this node');
  
          this._node = node;
          this._stickyMode = null;
          this._active = false;
  
          stickies.push(this);
  
          this.refresh();
      }
  
      _createClass(Sticky, [{
          key: 'refresh',
          value: function refresh() {
              if (seppuku || this._removed) return;
              if (this._active) this._deactivate();
  
              var node = this._node;
  
              /*
               * 1. Save node computed props
               */
              var nodeComputedStyle = getComputedStyle(node);
              var nodeComputedProps = {
                  position: nodeComputedStyle.position,
                  top: nodeComputedStyle.top,
                  display: nodeComputedStyle.display,
                  marginTop: nodeComputedStyle.marginTop,
                  marginBottom: nodeComputedStyle.marginBottom,
                  marginLeft: nodeComputedStyle.marginLeft,
                  marginRight: nodeComputedStyle.marginRight,
                  cssFloat: nodeComputedStyle.cssFloat
              };
  
              /*
               * 2. Check if the node can be activated
               */
              if (isNaN(parseFloat(nodeComputedProps.top)) || nodeComputedProps.display == 'table-cell' || nodeComputedProps.display == 'none') return;
  
              this._active = true;
  
              /*
               * 3. Check if the current node position is `sticky`. If it is, it means that the browser supports sticky positioning,
               *    but the polyfill was force-enabled. We set the node’s position to `static` before continuing, so that the node
               *    is in it’s initial position when we gather its params.
               */
              var originalPosition = node.style.position;
              if (nodeComputedStyle.position == 'sticky' || nodeComputedStyle.position == '-webkit-sticky') node.style.position = 'static';
  
              /*
               * 4. Get necessary node parameters
               */
              var referenceNode = node.parentNode;
              var parentNode = shadowRootExists && referenceNode instanceof ShadowRoot ? referenceNode.host : referenceNode;
              var nodeWinOffset = node.getBoundingClientRect();
              var parentWinOffset = parentNode.getBoundingClientRect();
              var parentComputedStyle = getComputedStyle(parentNode);
  
              this._parent = {
                  node: parentNode,
                  styles: {
                      position: parentNode.style.position
                  },
                  offsetHeight: parentNode.offsetHeight
              };
              this._offsetToWindow = {
                  left: nodeWinOffset.left,
                  right: document.documentElement.clientWidth - nodeWinOffset.right
              };
              this._offsetToParent = {
                  top: nodeWinOffset.top - parentWinOffset.top - parseNumeric(parentComputedStyle.borderTopWidth),
                  left: nodeWinOffset.left - parentWinOffset.left - parseNumeric(parentComputedStyle.borderLeftWidth),
                  right: -nodeWinOffset.right + parentWinOffset.right - parseNumeric(parentComputedStyle.borderRightWidth)
              };
              this._styles = {
                  position: originalPosition,
                  top: node.style.top,
                  bottom: node.style.bottom,
                  left: node.style.left,
                  right: node.style.right,
                  width: node.style.width,
                  marginTop: node.style.marginTop,
                  marginLeft: node.style.marginLeft,
                  marginRight: node.style.marginRight
              };
  
              var nodeTopValue = parseNumeric(nodeComputedProps.top);
              this._limits = {
                  start: nodeWinOffset.top + window.pageYOffset - nodeTopValue,
                  end: parentWinOffset.top + window.pageYOffset + parentNode.offsetHeight - parseNumeric(parentComputedStyle.borderBottomWidth) - node.offsetHeight - nodeTopValue - parseNumeric(nodeComputedProps.marginBottom)
              };
  
              /*
               * 5. Ensure that the node will be positioned relatively to the parent node
               */
              var parentPosition = parentComputedStyle.position;
  
              if (parentPosition != 'absolute' && parentPosition != 'relative') {
                  parentNode.style.position = 'relative';
              }
  
              /*
               * 6. Recalc node position.
               *    It’s important to do this before clone injection to avoid scrolling bug in Chrome.
               */
              this._recalcPosition();
  
              /*
               * 7. Create a clone
               */
              var clone = this._clone = {};
              clone.node = document.createElement('div');
  
              // Apply styles to the clone
              extend(clone.node.style, {
                  width: nodeWinOffset.right - nodeWinOffset.left + 'px',
                  height: nodeWinOffset.bottom - nodeWinOffset.top + 'px',
                  marginTop: nodeComputedProps.marginTop,
                  marginBottom: nodeComputedProps.marginBottom,
                  marginLeft: nodeComputedProps.marginLeft,
                  marginRight: nodeComputedProps.marginRight,
                  cssFloat: nodeComputedProps.cssFloat,
                  padding: 0,
                  border: 0,
                  borderSpacing: 0,
                  fontSize: '1em',
                  position: 'static'
              });
  
              referenceNode.insertBefore(clone.node, node);
              clone.docOffsetTop = getDocOffsetTop(clone.node);
          }
      }, {
          key: '_recalcPosition',
          value: function _recalcPosition() {
              if (!this._active || this._removed) return;
  
              var stickyMode = scroll.top <= this._limits.start ? 'start' : scroll.top >= this._limits.end ? 'end' : 'middle';
  
              if (this._stickyMode == stickyMode) return;
  
              switch (stickyMode) {
                  case 'start':
                      extend(this._node.style, {
                          position: 'absolute',
                          left: this._offsetToParent.left + 'px',
                          right: this._offsetToParent.right + 'px',
                          top: this._offsetToParent.top + 'px',
                          bottom: 'auto',
                          width: 'auto',
                          marginLeft: 0,
                          marginRight: 0,
                          marginTop: 0
                      });
                      break;
  
                  case 'middle':
                      extend(this._node.style, {
                          position: 'fixed',
                          left: this._offsetToWindow.left + 'px',
                          right: this._offsetToWindow.right + 'px',
                          top: this._styles.top,
                          bottom: 'auto',
                          width: 'auto',
                          marginLeft: 0,
                          marginRight: 0,
                          marginTop: 0
                      });
                      break;
  
                  case 'end':
                      extend(this._node.style, {
                          position: 'absolute',
                          left: this._offsetToParent.left + 'px',
                          right: this._offsetToParent.right + 'px',
                          top: 'auto',
                          bottom: 0,
                          width: 'auto',
                          marginLeft: 0,
                          marginRight: 0
                      });
                      break;
              }
  
              this._stickyMode = stickyMode;
          }
      }, {
          key: '_fastCheck',
          value: function _fastCheck() {
              if (!this._active || this._removed) return;
  
              if (Math.abs(getDocOffsetTop(this._clone.node) - this._clone.docOffsetTop) > 1 || Math.abs(this._parent.node.offsetHeight - this._parent.offsetHeight) > 1) this.refresh();
          }
      }, {
          key: '_deactivate',
          value: function _deactivate() {
              var _this = this;
  
              if (!this._active || this._removed) return;
  
              this._clone.node.parentNode.removeChild(this._clone.node);
              delete this._clone;
  
              extend(this._node.style, this._styles);
              delete this._styles;
  
              // Check whether element’s parent node is used by other stickies.
              // If not, restore parent node’s styles.
              if (!stickies.some(function (sticky) {
                  return sticky !== _this && sticky._parent && sticky._parent.node === _this._parent.node;
              })) {
                  extend(this._parent.node.style, this._parent.styles);
              }
              delete this._parent;
  
              this._stickyMode = null;
              this._active = false;
  
              delete this._offsetToWindow;
              delete this._offsetToParent;
              delete this._limits;
          }
      }, {
          key: 'remove',
          value: function remove() {
              var _this2 = this;
  
              this._deactivate();
  
              stickies.some(function (sticky, index) {
                  if (sticky._node === _this2._node) {
                      stickies.splice(index, 1);
                      return true;
                  }
              });
  
              this._removed = true;
          }
      }]);
  
      return Sticky;
  }();
  
  /*
   * 5. Stickyfill API
   */
  
  
  var Stickyfill = {
      stickies: stickies,
      Sticky: Sticky,
  
      forceSticky: function forceSticky() {
          seppuku = false;
          init();
  
          this.refreshAll();
      },
      addOne: function addOne(node) {
          // Check whether it’s a node
          if (!(node instanceof HTMLElement)) {
              // Maybe it’s a node list of some sort?
              // Take first node from the list then
              if (node.length && node[0]) node = node[0];else return;
          }
  
          // Check if Stickyfill is already applied to the node
          // and return existing sticky
          for (var i = 0; i < stickies.length; i++) {
              if (stickies[i]._node === node) return stickies[i];
          }
  
          // Create and return new sticky
          return new Sticky(node);
      },
      add: function add(nodeList) {
          // If it’s a node make an array of one node
          if (nodeList instanceof HTMLElement) nodeList = [nodeList];
          // Check if the argument is an iterable of some sort
          if (!nodeList.length) return;
  
          // Add every element as a sticky and return an array of created Sticky instances
          var addedStickies = [];
  
          var _loop = function _loop(i) {
              var node = nodeList[i];
  
              // If it’s not an HTMLElement – create an empty element to preserve 1-to-1
              // correlation with input list
              if (!(node instanceof HTMLElement)) {
                  addedStickies.push(void 0);
                  return 'continue';
              }
  
              // If Stickyfill is already applied to the node
              // add existing sticky
              if (stickies.some(function (sticky) {
                  if (sticky._node === node) {
                      addedStickies.push(sticky);
                      return true;
                  }
              })) return 'continue';
  
              // Create and add new sticky
              addedStickies.push(new Sticky(node));
          };
  
          for (var i = 0; i < nodeList.length; i++) {
              var _ret2 = _loop(i);
  
              if (_ret2 === 'continue') continue;
          }
  
          return addedStickies;
      },
      refreshAll: function refreshAll() {
          stickies.forEach(function (sticky) {
              return sticky.refresh();
          });
      },
      removeOne: function removeOne(node) {
          // Check whether it’s a node
          if (!(node instanceof HTMLElement)) {
              // Maybe it’s a node list of some sort?
              // Take first node from the list then
              if (node.length && node[0]) node = node[0];else return;
          }
  
          // Remove the stickies bound to the nodes in the list
          stickies.some(function (sticky) {
              if (sticky._node === node) {
                  sticky.remove();
                  return true;
              }
          });
      },
      remove: function remove(nodeList) {
          // If it’s a node make an array of one node
          if (nodeList instanceof HTMLElement) nodeList = [nodeList];
          // Check if the argument is an iterable of some sort
          if (!nodeList.length) return;
  
          // Remove the stickies bound to the nodes in the list
  
          var _loop2 = function _loop2(i) {
              var node = nodeList[i];
  
              stickies.some(function (sticky) {
                  if (sticky._node === node) {
                      sticky.remove();
                      return true;
                  }
              });
          };
  
          for (var i = 0; i < nodeList.length; i++) {
              _loop2(i);
          }
      },
      removeAll: function removeAll() {
          while (stickies.length) {
              stickies[0].remove();
          }
      }
  };
  
  /*
   * 6. Setup events (unless the polyfill was disabled)
   */
  function init() {
    
      if (isInitialized) {
          return;
      }
  
      isInitialized = true;
  
      // Watch for scroll position changes and trigger recalc/refresh if needed
      function checkScroll() {
          if (window.pageXOffset != scroll.left) {
              scroll.top = window.pageYOffset;
              scroll.left = window.pageXOffset;
  
              Stickyfill.refreshAll();
          } else if (window.pageYOffset != scroll.top) {
              scroll.top = window.pageYOffset;
              scroll.left = window.pageXOffset;
  
              // recalc position for all stickies
              stickies.forEach(function (sticky) {
                  return sticky._recalcPosition();
              });
          }
      }
  
      checkScroll();
      window.addEventListener('scroll', checkScroll);
  
      // Watch for window resizes and device orientation changes and trigger refresh
      window.addEventListener('resize', Stickyfill.refreshAll);
      window.addEventListener('orientationchange', Stickyfill.refreshAll);
  
      //Fast dirty check for layout changes every 500ms
      var fastCheckTimer = void 0;
  
      function startFastCheckTimer() {
          fastCheckTimer = setInterval(function () {
              stickies.forEach(function (sticky) {
                  return sticky._fastCheck();
              });
          }, 500);
      }
  
      function stopFastCheckTimer() {
          clearInterval(fastCheckTimer);
      }
  
      var docHiddenKey = void 0;
      var visibilityChangeEventName = void 0;
  
      if ('hidden' in document) {
          docHiddenKey = 'hidden';
          visibilityChangeEventName = 'visibilitychange';
      } else if ('webkitHidden' in document) {
          docHiddenKey = 'webkitHidden';
          visibilityChangeEventName = 'webkitvisibilitychange';
      }
  
      if (visibilityChangeEventName) {
          if (!document[docHiddenKey]) startFastCheckTimer();
  
          document.addEventListener(visibilityChangeEventName, function () {
              if (document[docHiddenKey]) {
                  stopFastCheckTimer();
              } else {
                  startFastCheckTimer();
              }
          });
      } else startFastCheckTimer();
  }
  
  if (!seppuku) init();
  
  /*
   * 7. Expose Stickyfill
   */
  if (typeof module != 'undefined' && module.exports) {
      module.exports = Stickyfill;
  } else if (isWindowDefined) {
      window.Stickyfill = Stickyfill;
  }
  
})(window, document);